Somewhat related, I've been fond of flat-file or file-based configs as well. Such as Nagios/Icinga has configuration files, but now seem to suggest a database & UI/API.

File-based config made scripting the generation of the configs pretty easy and updating for changes by just overwriting the files and reloading the daemon.

IIRC, similarly TWiki also uses individual files for the pages and configs with RCS (Revision Control System) per-file to track changes.